public class Two {
    int m,n;
    int[] dy={0,0,1,-1};
    int[] dx={1,-1,0,0};
    boolean[][] vis=new boolean[199][199];

    public int solve (char[][] grid) {
        m=grid.length;
        n=grid[0].length;
        int ret =0;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j]=='1'&&!vis[i][j]) {
                    ret++;
                    dfs(grid,i,j);
                }
            }
        }
        return ret;
    }

    private void dfs(char[][] grid, int i, int j) {
        vis[i][j]=true;
        for (int k = 0; k < 4; k++) {
            int x=i+dx[k],y=j+dy[k];
            if (x>=0&&x<m&&y>=0&&y<n&&grid[x][y]=='1'&&!vis[x][y]){
                dfs(grid,x,y);
            }
        }
    }
}
